Micro-level tailoring of lithium ion extraction/insertion compounds and characterization of battery performance by microelectrode techniques with single particle electrodes

本研究项目的目标是开发适用于电动汽车的锂离子二次电池的新材料，基于两种新技术，一种是用于材料制备的柠檬酸盐前体方法，另一种是用于粉末电池材料电化学表征的微电极技术。(1)Yamagata团队合作，通过改进的柠檬酸盐法获得了具有良好循环性能的镍酸锂和尖晶石型锂锰氧化物，使我们能够系统地制备具有微观剪裁和原子级均匀性的多组分氧化物。(2)Tohoku集团开发了微电极技术，该技术在电化学表征和快速搜索定制样品方面非常通用，即使是少量的微米尺寸颗粒。由于伴随着锂离子的插入/拔出的机械不稳定性而导致的颗粒分裂的原位观察，高电位（105 V）伏安法以检查颗粒在有机溶液中的电化学稳定性，通过AC和电位阶跃法测定锂离子在固相中的扩散系数，并利用微阵列电极技术对锂离子嵌入过程进行了原位拉曼光谱和原位电导测量。由此获得的数据被反馈给合作伙伴，并有效地用于进一步的研发。

The present research project has aimed development of new materials for the lithium-ion secondary battery, which is applicable to electric vehicles, based on two novel techniques, one being the citrate precursor method for material preparation and the other a microelectrode technique for electrochemical characterization of powdered battery materials.(1) Under collaboration, Yamagata group obtained lithium nickelate and spinel-related lithium manganese oxides with good cyclability by the modified citrate method, which enabled us to prepare systematically the multi-components oxides with micro-level tailoring and atomic-level homogeneity.(2) Tohoku group has developed microelectrode techniques which are very versatile in electrochemical characterization and rapid searching tailored samples even in a small quantity of micro-meter size particles. In-situ observation of particle splitting due to the mechanical instability accompanied by the insertion/extraction of lithium ions, high potential (〜5V) voltammetry to examine the electrochemical stability of the particle in organic solutions, determination of diffusion coefficients of lithium ions in the solid phase by AC and potential step method, and in-situ Raman spectroscopy and in-situ conductivity measurements during insertion of lithium ions with micro-array electrode technique also have been carried. Data thus obtained were feedbacked to the partners and effectively utilized in further R&D.